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UNITED STATES PATENT OFFICE,

FREDERICK WINTERIIOFF, Ol LONDON, COUNTY OF MIDDL ISEX, ENGLAND.

PROCESS OF ETCHlNG OR ENGRAVING ON GLASS, 80C.

SPECIFICATION forming part of Letters Patent No. 41 1,560, datedSeptember 24, 1889.

Application filed January 12, 188B. Renewed May 2, 1889. Serial No.309,412. (No specimens. Patented in England May 3, 1886, No. 5,978.

To to whom it may concern:

lie it known that I, FREDERICK \VINTER- IIOFF, a subject of the Emperorof (liermany, and a resident of London, in the county of Middlescx,England, have invented certain new and usefulImprovements inthelrocessts of Etching or Engraving on. Glass and Like Substances, (forwhich I have obtained a patent in Great vBritain, No. 5,978, dated May3, 1886,) of which the following is a full, clear, and exactspecification.

My invention relates to a process of etching, &c.

lieretofore glass and other surfaces have in some cases been etched byfirst covering the surface with a protecting coating, then removingparts from the protecting coating where the glass or othcrsurfaco is tobe etched or eaten away, and then etching out the exposed surface withiluoric or other acid. Glass and other surfaces have also been coatedwith a solution of a substance-such as asphalt-which is renderedinsoluble when acted on by light. A photographic negative has beenplaced over the coated surface and exposed to light. Part of the coatinghas so been rendered insoluble. The remainder has been dissolved away,and the parts of the glass or other surface so left exposed have beenetched or eaten away with fiuoric or other facid. These processes areslow and costly.

By my invention I am able to greatly increase the rate at which etchedwork can be produced.

For engraving or etching upon glass or upon brass, copper, Zinc, orother metal plates, or upon marble, granite, or other substance whichcan be eaten away by acid,I first clean the substance or article to beetched and coat the same with a solution of asphalt, bichromate-black,or any other substance affected or hardened by exposure to sunlight andwhich is impervious to acids, and allow the same to dry in the dark.Preferably I use a solution in ado by dissolving about four pounds offinely-powdered asphalt in three pints of spirits of turpentine, boilingit gently for about three hours, and then adding and well stirring inhall apintof spirits of turpentine. Afterward the solution should befiltered through muslin while hot, and should be kept in stoppcrcdbottles away from the light. I also draw or engrave the matter to beetched on a lithogra 'ihic stone or on a zinc or steel plate, orotherwise form a printing plate, block, or stamp, with which copies ofthe design or pattern to be etched can be printed. I then print withprinting-ink from the stone or plate or block onto lithographictransferpaper as many impressionsas are required of the matter to beetched. I then transfer the printed matter from the transfer-paper ontothe coating on the article. I then dust or cover the transferred matterover with bronzepowdor, gold or other metal leaf, or any linclygroundpowder which will obstruct the passage of light, and then carefullywashit, when it will be found that the bronze-powder or whatever else isused has adhered only to the printed matter and forms above it a surfaceimpervious to light. I then place the article with the coated sidetoward the sunlight, the result being that the exposed surface of theasphaltum coating is hardened; but the portion covered bythebronze-powder, being protected from the action of the light, remainssoft. I then with a stilt brush and paraflineoil brush out the softportion, which is the printed matter retpiired to be etched, and it isthen ready for aciding in the usual way, the remaining hard portion ofthe coating being removed afterward by a soda bath or by turpentine, orin other ordinary ways.

If the design or pattern to be engraved is of a broad distinct nature, afairly good result can be obtained even when the transferred printerdesign is not afterward coated with the bronze or other powder; but inall cases I prefer to use the bronze or other powder, as far betterresults are obtained by its use.

liaving now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be performed, I declare thatwhat I claim is The process of etching, consisting of coating thearticle with an acid-resisting substance, then transferring 0E a printeddesign or picture onto the coated surface from tra nsfer-paper, and thendusting over or covering this transferred design with metal leaf or withbronze powder or other finely ground powder which will obstruct thepassage of light, and subsequently exposing the surface to light anddissolving out such parts of the coating as arenot thereby renderedinsoluble,

I0 then etching out the exposed portions of the have hereunto set myhand this 12th day of August, 1887.

FREDERICK \V'IN'lhlRlIUhL.

Witnesses:

SILo IIERMANN KELLER, HENRY HEAL.

